The biological activity of a wide variety of N-alkyl carbamate compounds is well known. N-methyl carbamate compounds exhibit outstanding insecticidal activity. Among the more important N-methyl carbamate insecticides are aldicarb, carbaryl methomyl, carbofuran, landrin, and the like.
The most common conventional process for producing these compounds is by the reaction of an N-alkyl isocyanate with the appropriate active hydrogen containing compound. Many of these isocyanate reactants are highly reactive, resulting in syntheses with high product yields. However, the reactive nature of these compounds, particularly with water, often necessitates special precautions in their transportation, storage, and handling.
The Aldicarb synthesis process is illustrative. Aldicarb can be prepared by reacting methyl isocyanate (MIC) with 2-methyl-2-(methylthio) propionaldehyde oxime. Using this process, good yields are attainable in large scale production of this pesticide. However, special care must be exercised in transporting and sorting MIC, and in handling it.
This invention is directed to a process for preparing N-alkyl carbamate compounds without the use of N-alkyl isocyanate reactants. The sulfonate salts used as reactants in this process are stable solids and can be transported and stored without exercising special precautions. Another advantage is that the sulfonate salts are water soluble and the reactions in accordance with the present invention can be conducted using a water solvent.